Conveyors for moving particulate material such as stone, sand or gravel can be found in various applications. A truck with a conveyor apparatus as known in the art is disclosed in U.S. Pat. No. 5,190,432. This patent discloses an optional attachment for a standard dump truck that includes a swing arm, pivotally connected to the truck's chassis, an elongated frame pivotally connected to the swing arm and mounting an endless conveyor belt.
Another application where conveyors are used to move particulate material is a stone slinger. A stone slinger includes a first conveyor that receives material from a hopper, which is located behind the cab of a truck. The first conveyor moves the material onto a second conveyor. The second conveyor then sprays the material from the back end of the truck.
Stone slingers are used so that the particulate material can be projected from the rear of a dump truck or similar device to a desired location. The slinger has a limited dispensing range that is determined by the speed of the conveyor.
Material is usually dumped onto the conveyor from a hopper or another conveyor. The method in which the material is loaded onto the conveyor from the truck causes it to bounce along the conveyor rather than rest on it. This can cause some material to be projected from the conveyor prematurely in all directions. This creates a hazard to anyone standing in the vicinity of the slinger. An increase in the conveyor speed causes further erratic discharge of material. Therefore, the speed of the conveyor is limited thereby limiting the discharge range of the slinger.
Some attempts have been made to control the premature and erratic discharge of material from the conveyor. In one such method, the material is sandwiched between the conveyor belt and a cover that is made of relatively light material such as sheet metal. The cover lies flat on the belt, while maintaining its horizontal position, and is temporarily displaced as the material passes underneath it. This method does not effectively control the erratic and premature discharge of material.
Thus, a need exists for a device for controlling the erratic dispersion of particulate material being conveyed on a conveyor belt. Such a device would reduce any impediment in increasing the speed of the conveyor belt and, thereby, allow material to be ejected farther.